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N-Halosuccinimide/BF3-H2O, Efficient Electrophilic Halogenating Systems for Aromatics

G. K. Surya Prakash,* Thomas Mathew, Dushyanthi Hoole, Pierre M. Esteves, Qi Wang, Golam Rasul and George A. Olah

*Donald P. and Katherine B. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, Los Angeles, California 90089-1661, Email: gprakashusc.edu

G. K. S. Prakash, T. Mathew, D. Hoole, P. M. Esteves, Q. Wang, G. Rasul, G. A. Olah, J. Am. Chem. Soc., 2004, 126, 15770-15776.

DOI: 10.1021/ja0465247

Abstract

N-Halosuccinimides are efficiently activated in trifluoromethanesulfonic acid and BF3-H2O, allowing the halogenations of deactivated aromatics. BF3-H2O is more economic, easy to prepare, nonoxidizing, and offers sufficiently high acidity.

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Details

The document discusses the development of an efficient halogenating system using N-halosuccinimides (NXS) activated by boron trifluoride monohydrate (BF3-H2O) for the halogenation of deactivated aromatics. The study, conducted by researchers from the University of Southern California and Universidade Federal do Rio de Janeiro, highlights the advantages of BF3-H2O, which is economical, easy to prepare, nonoxidizing, and offers high acidity. The combination of NXS/BF3-H2O was found to be effective for chlorination, bromination, and iodination of various deactivated aromatics under mild conditions, providing high yields of monohalogenated products. Theoretical calculations using DFT methods suggest that protonated NXS undergo further protosolvation to form highly reactive superelectrophilic species, facilitating the transfer of halogen cations (X+) to the aromatic substrates. The study also includes experimental procedures and computational details, confirming the efficiency and selectivity of the NXS/BF3-H2O system for aromatic halogenation. The research was supported by the Loker Hydrocarbon Research Institute and the National Science Foundation, with additional financial support from Brazilian agencies CNPq and FAPERJ.

Key Words

Chlorination, Bromination, Iodination, NBS, NCS, NIS

ID: J48-Y2004-1870